Self Ignition temp of HHO - Diesel Tech help please.

[JojoJaro]

Folks, as you probably know I have an EFILive system monitoring my Duramax engine parameters as I drive. I noticed that when I 'coast' (no throttle), there is no injected fuel, either for the main injection or the pilot injection. The mm3 reading is zero. Since the way I drive (to maintain constant speed) is: push the pedal then coast, push then coast, push then coast, etc. I am wondering what will happen to the the HHO enriched air during the time the cylinder is not receiving diesel?

I'm theorizing, that during the time diesel is being injected, the first minute amount of diesel will self-ignite first, then ignites the HHO, which would then ignite the remainder of the diesel completely burning everything. This would happen because the HHO flame propagation rates are significantly faster than diesel, which means HHO will ignite completely before diesel has a chance to completely ignite.

Now, during the time when diesel in not being injected, what you have in the cylinder that is being compressed is HHO enriched air. This would be enriched according to the proportion of output of your gen.

Question is: what happens to this HHO enriched air as it is compressed. Will it self-ignite on its own without diesel? The air is compressed to temperatures hot enough to achieve diesel self ignition, but what about HHO enriched air. Will air inside the cylinder be hot enough to achieve HHO self ignition?

I've read that hydrogen concentrations below 4% will not achieve self ignition. Is this correct? And since we are not reaching 4% concentrations in our gen designs, does that mean the HHO-enriched air simply passes out the exhaust. Or worse, will it self-ignite before the piston reaches TDC causing pinging.

For folks will diesel trucks, have you noticed pinging due to 'premature detonation' of the HHO-enriched air as it is being compressed in the cylinder? What LPM output do you have so that I can guesstimate the level of concentration that would possibly cause this premature detonation.

[timetowinarace]

I monitor my Cummins diesel with the Bullydog Outlook. Injection Control Pressure (ICP) is something I've monitored ever since my truck was new. It never shows 0(zero) unless the truck is not running. With no fuel pedal pressure, the ICP is at idle pressure wich is just under 1 psi. While I'm not that familur with the duramax, I don't find it possible that there is no fuel pressure, thus no fuel, when the throttle is not pushed. It is more likely that your EFILive will not measure the .6 to .9 psi needed to idle and reads a zero pressure.

Other than that, I agree with your basic theory of compressed diesel igniting the hho. But at no time in a diesel engine will there be no diesel in the cylinders unless the fuel pump is shut off. Stopping the fuel is the only way to turn off a diesel engine. Once they are started, you can disconnect all electrical components and they will continue to run (provided the fuel pump is a mechanical one).

[Farmercal]

Stopping the fuel is the only way to turn off a diesel engine. Once they are started, you can disconnect all electrical components and they will continue to run (provided the fuel pump is a mechanical one). Every diesel engine I have ever shut down was done by flooding the engine with too much fuel. I though that it was a bad thing to deprive a diesel engine of fuel. Have things changed that much?

[timetowinarace]

Every diesel engine I have ever shut down was done by flooding the engine with too much fuel. I though that it was a bad thing to deprive a diesel engine of fuel. Have things changed that much?


????

I don't believe anything has changed. I've used many an old tractor and when the pull lever to stop the engine is broken we simply get off and pull it by hand at the injection pump as they are mechanical. As far as I am aware there are no butterly valves to regulate the air intake like on a gasoline engine. the throttle goes directly to the injection pump. The only way to 'flood' an engine with fuel would be to deprive it of air. To simply pour more fuel to it would cause the rpms to run away. It would also be very difficult to restart the engine with a puddle of fuel in each cylinder. Not to mention the fuel getting past the piston rings and into the engine oil making it diluted and useless.

It is a bad thing for a diesel to run out of fuel. It has nothing to do with the engine itself though. It is because it takes considerable time and work to get fuel back into the injection system. The injection system fills with air and on older diesels each phase of the injection system must be bled to get the air out from the fuel tank to the filter to the injection pump to each injector. Very much like bleeding your brake lines. I've done this a few times and it's not fun. On newer diesels this is not as much of an issue because of the high pressure pumps but it still takes considerable time and a lot of engine cranking to get the system reprimed.

[Farmercal]

Thanks for info Timetowinarace. So when you pull that knob on the diesel engines you are stopping the flow of fuel into the combustion chamber? I guess when they told me they had to choke it they meant literally choke it so it didn't have any more fuel. You sure learn a lot on these forums!

[JojoJaro]

I monitor my Cummins diesel with the Bullydog Outlook. Injection Control Pressure (ICP) is something I've monitored ever since my truck was new. It never shows 0(zero) unless the truck is not running. With no fuel pedal pressure, the ICP is at idle pressure wich is just under 1 psi. While I'm not that familur with the duramax, I don't find it possible that there is no fuel pressure, thus no fuel, when the throttle is not pushed. It is more likely that your EFILive will not measure the .6 to .9 psi needed to idle and reads a zero pressure.

Other than that, I agree with your basic theory of compressed diesel igniting the hho. But at no time in a diesel engine will there be no diesel in the cylinders unless the fuel pump is shut off. Stopping the fuel is the only way to turn off a diesel engine. Once they are started, you can disconnect all electrical components and they will continue to run (provided the fuel pump is a mechanical one).


On my EFILIve, I am able to monitor

1. Main injection Time - The amount of time the injector is open to feed diesel for the main injection - usually 200-800 ms
2. Pilot Injection Time - The amount of time the injector is open to feed diesel for the pilot injection - usually 100-300 ms
3. Main injection mm3 - The amount of fuel being injected (in cu mm) during the time the injectors are open for the main injection - usually 5 - 40 mm3
4. Pilot Injection mm3 - The amount of fuel being injected during the time the injectors are open for the pilot injection - usually 1 mm3


During idle, these four values are non-zero, but they are minimal. However, when on highway speeds and then coasting, these values display zero. So, while coasting, the engine does not have to do any work, so the injectors are not told to open either for pilot or main injection. The cylinders are not receiving any fuel while coasting.

I suspect it is the same on your Cummins (on late model Cummins) since it is also a common rail system designed by Bosch. The ECM programming for Bosch common rail is similar. Only actual values in the tables are different to account for various differences in the engine design. The common rail operating parameters and behavior is similar since they both come from Bosch.

So, in fact, on your Cummins, you will also have zero fuel while coasting. If you are injecting HHO and have not experienced premature detonation and pinging, then maybe the HHO concentration is simply too diluted to self-ignite in the cylinder.

But if they are self-igniting, and self-igniting at the right time (after TDC), then maybe this will add a little power to the engine while it is coasting. Enough power to allow you to coast a little longer effectively running your engine on HHO alone for a few more seconds. This obviously will increase your MPG, since you are travelling while not using a drop of diesel.

The purpose of my original post is to try to understand if this phenomenom is occuring during coasting. If it is, then that is good news and would mean that the more HHO you can inject, the longer you can coast. There might even be an LPM output high enough to allow you to coast indefinitely (as long as you do not need too much power, like hills, or against wind, etc.)

This phenomenom of providing a little power during coasting might explain the MPG gains attributed to HHO. Just imagine how high your MPG could get if the engine can be run on pure HHO just as if it was coasting. No fuel input while your engine is providing power just enough to coast longer.

[timetowinarace]

"The cylinders are not receiving any fuel while coasting."

"So, in fact, on your Cummins, you will also have zero fuel while coasting."

I'm going to have to disagree with those two statements. The engine or ecu does not know if the truck is coasting or simply at idle. It knows what the throttle position is. The fuel in the cylinders is the same for coasting or idle. Also, if while coasting there is zero fuel going to the cylinders as you claim the engine could not run. therefore it would have to restart, or in essence pushstart. Because of the high compression in diesels it isn't easy to push/pull start them and the reason there are two batteries in them is because the starters need a large amperage to overcome the high compresion. If there was no fuel to the engine, the compression would slow the vehicle quite quickly.

I'm kind of curious as to how you will explain how the engine runs without fuel?

[JojoJaro]

"The cylinders are not receiving any fuel while coasting."

"So, in fact, on your Cummins, you will also have zero fuel while coasting."

I'm going to have to disagree with those two statements. The engine or ecu does not know if the truck is coasting or simply at idle. It knows what the throttle position is. The fuel in the cylinders is the same for coasting or idle. Also, if while coasting there is zero fuel going to the cylinders as you claim the engine could not run. therefore it would have to restart, or in essence pushstart. Because of the high compression in diesels it isn't easy to push/pull start them and the reason there are two batteries in them is because the starters need a large amperage to overcome the high compresion. If there was no fuel to the engine, the compression would slow the vehicle quite quickly.

I'm kind of curious as to how you will explain how the engine runs without fuel?


Look, I have hundreds of hours of EFILive logging data that shows this. If you can download the EFILive viewer, I can send you some of my logs and you can see for yourself. I have captured many other parameters like Vehicle speed and throttle position. You can verify what I'm talking about. (Alternatively, if you are ever near Knoxville, give me a shot and I can bring you around town with the logging turned on.)

While coasting, the engine is being rotated by the momentum of the vehicle. That is why, the vehicle eventually slows down much faster than can be attributed to wind or friction, etc. This is how 'engine breaking' works. The truck is slowed down by the effort it has to do to compress the cylinders. While coasting the fuel will cut out and then as you slow down to a certain speed, the engine will resume 'idle' mode and start supplying fuel again. That is why it does not die.

It is a relatively simple matter for the ECM to know if you are coasting or idling - vehicle speed is the primary input. If your throttle position is zero and you are above a certain speed, then ECM decides that you are coasting. As you slow down further and reach the low speed cutoff, the ECM decides you are idling. Very simple. I can see this in my EFILive logs.

I am 100% sure, no fuel in being supplied to the cylinders when coasting.

[mario brito]

Look, I have hundreds of hours of EFILive logging data that shows this. If you can download the EFILive viewer, I can send you some of my logs and you can see for yourself. I have captured many other parameters like Vehicle speed and throttle position. You can verify what I'm talking about. (Alternatively, if you are ever near Knoxville, give me a shot and I can bring you around town with the logging turned on.)

While coasting, the engine is being rotated by the momentum of the vehicle. That is why, the vehicle eventually slows down much faster than can be attributed to wind or friction, etc. This is how 'engine breaking' works. The truck is slowed down by the effort it has to do to compress the cylinders. While coasting the fuel will cut out and then as you slow down to a certain speed, the engine will resume 'idle' mode and start supplying fuel again. That is why it does not die.

It is a relatively simple matter for the ECM to know if you are coasting or idling - vehicle speed is the primary input. If your throttle position is zero and you are above a certain speed, then ECM decides that you are coasting. As you slow down further and reach the low speed cutoff, the ECM decides you are idling. Very simple. I can see this in my EFILive logs.

I am 100% sure, no fuel in being supplied to the cylinders when coasting.

I'm not a mechanical enginier, nor do I pretend to know anything about engines above the basic's, but I've tested about the difference between coasting and idling.

Last year I saw a Top Gear's episode that states the exact same thing. So, me and a friend of mine decided to run a few tests to see if that was true.

He's got an Opel Vectra Turbo-Diesel latest model. We went to some long downhill road's near Lisbon. Please do not forget that we all have manual gear shifting.

While running downhill in 6th gear without pressing the gas pedal, the on-board computer showed a 0.0 liters / 100 Km instant consumption. While doing the same, but in neutral, it showed 0.4 liters / Hour instant consumption.

The fact that the computer switched the instant consumption from "/ 100Km" to "/ Hour" shows that it can "see" the difference. Maybe there's another explanation, but that's what the computer showed several times.

I hope that this helps.

Thanks

[wrxdrvr]

I am going to stick my nose into this, even tho I have zero computer knowledge...If there actually was no fuel being injected there would be MAJOR engine braking like in the big rigs so even tho it shows 0% for fuel being injected there has to be some. It's just that their 0% is not actually zero fuel... :)

[JojoJaro]

I am going to stick my nose into this, even tho I have zero computer knowledge...If there actually was no fuel being injected there would be MAJOR engine braking like in the big rigs so even tho it shows 0% for fuel being injected there has to be some. It's just that their 0% is not actually zero fuel... :)

Not necessarily. The transmission could be disengaging while coasting. I know that on my transmission (4L85E), engine braking is not an option. If I bought a 3500 Sierra with Allison 1000 tranny, engine braking is an option. And remember, engine braking only activates if you specifically told the tranny you want it, by activating 'Tow/Haul' mode on the Allison 1000 tranny.

So, the absense of major engine braking could simply mean that the transmission is disengaging.

As for the sensitivity of the reading. The computer can recognize down to .1 mm3 of injected fuel. The injectors themselves do not have the resolution to inject this amount of miniscule fuel. So, it is improbable that what you are saying is true.

I believe zero reading means zero fuel injected.

[wrxdrvr]

I believe zero reading means zero fuel injected.

You could be right... :) My thought about the HHO is that it would ignite, just like the diesel would when injected...

[timetowinarace]

I believe the zero reading your getting is a baseline minimum. All other readings are positive readings above the baseline. Meaning no additional fuel above the baseline is being injected while coasting. The reason there is a positive reading while at idle is because the ecu injects additional fuel to maintain a certain rpm.

If the transmission was disengageing while coasting, it would not turn the engine, thus with no fuel the engine would not run.

I have an exhaust brake (the same principle as an engine brake only it's on the exhaust and not the intake) on my truck. On cold mornings I can turn it on and it will create back pressure to hold heat and warm the engine faster. The sound it makes is distictive. For engine braking, it closes off the exhaust the same way. The backpressure created is due to the inability of the exhaust gasses to escape as easily. If there was no fuel, there would be no exhaust gasses, there would be no engine braking.

Aftermarket exhaust brakes are available for all deisel trucks. It is not the engine that determines whether they can be used, it is the transmission.

Is it possible that I am wrong? Sure. I highly doubt it though.

I don't know why I hadn't thought of this before. I monitor EGT"s (exhaust gas temperature) very closely in my truck because it is rarely driven without pulling a trailer. I use a programmer to increase horsepower. My EGT's never drop below 350* no matter how long the downgrade. This is also the idle temp. I am inclined to believe that if there was no fuel injected while coasting down 3 miles of 6% grade, my EGT's would reflect this. They do not. They show a steady temp of 350* indicating combustion in the cylinders.

[mario brito]

If the transmission was disengageing while coasting, it would not turn the engine, thus with no fuel the engine would not run.



While coasting in neutral , the computer switched to 0.4 L / Hour.
It was when coasting in 6th gear, that it showed 0.0 L / 100 Km.

As I said, I'm not even close to be an expert on this. I'm just telling what I saw.

Thanks

[timetowinarace]

From wiki:

In cars with a manual transmission, fuel can be saved while the car is coasting in gear. This is because the car's movement is keeping the engine rotating, so there is no need to use fuel for this purpose. Control units on modern transmissions recognize this and stop all fuel flow to the engine when possible. (Automatic transmission cars rely on torque converters, not clutches, to transmit power from the engine to the gearbox, and whereas clutches can transmit power in both directions, torque converters, especially when tuned as they are in cars, are not good at transmitting power in the opposite direction.)

[timetowinarace]

I stand corrected. There are situations when zero fuel goes to the cylinders.

[buffordboy23]

I've read that hydrogen concentrations below 4% will not achieve self ignition. Is this correct? And since we are not reaching 4% concentrations in our gen designs, does that mean the HHO-enriched air simply passes out the exhaust. Or worse, will it self-ignite before the piston reaches TDC causing pinging.


The 4% is the lower flammability limit for hydrogen. This 4% figure is only useful around standard conditions, about 20 degrees Celsius (68 degrees Fahrenheit). High pressure and temperature, such as that inside an engine, can change this figure significantly, thus lowering the flammability limit. Therefore, the hydrogen will combust inside an engine.

Pre-ignition could be a possibility under the right conditions due to something such as hot spots on the cylinder walls; the minimum ignition energy of hydrogen is 0.02 mJ. I would guess that if the pressure and temperature changes of the combustion gases during the compression stroke lowered the flammability limit to ignition levels long before TDC, pre-ignition would be more likely. Tables or graphs can probably be found somewhere on the internet that show how the flammability limit changes with pressure and temperature. Hydrogen can spontaneously combust at temperatures close to 600 degrees Celsius.

[JojoJaro]

OK, I found out from the technical manuals and observations for my Duramax the following.

1. When coasting, no fuel is being injected until vehicle speed is 43 MPH. At speeds between 25 - 43 MPH, there is partial injection of pilot as well as main injection. By partial, I mean, it will inject for a second and then cut off of a second or 2 and then inject for a second or so again and cut off again, until 25 MPH where it resumes 'Idle' mode injection.

2. On my Duramax (van), the engine provide minimal engine braking when coasting. The tranny does not disengage. I found out that to achieve full engine braking like those on the Sierra, the turbo vanes will close providing the full back pressure for engine braking. My van does not have this feature supposedly because the tranny is not strong enough to hold under the intense back pressure provided by the closed turbo vanes.

3. Main injection times for my Duramax are between 100 - 800 microseconds wherein it injects 10 - 50 mm3 of fuel most of the time. When pushed hard, injectors open for 1200 microseconds and injects over 60 mm3 of fuel.

4. My pilot injection times are 80-400 microseconds where it injects between .8 - 1 mm3 of fuel. The pilot injection occurs about 800-1200 microseconds before the main injection.

5. The main injection timing is between 1 to 11 degree after TDC.

6. There is no such thing a baseline and only recording what is above the baseline. The ECM does report the actual fuel injected. I have confirmed this by matching the injected fuel to the calibration tables. So the values I am reading are the actual values, not the delta above a baseline.